Chain stitch sewing machine



Oct. 3, 1933. F. LUTZ CHAIN STITCH SEWING MACHINE Filed Aug. 21,1931 5 Sheets-Sheet 1 mam/ f attorneys- 6 Sheets-Sheet 2 F. LUTZ CHAIN STITCH SEWING MACHINE Fil'd Aug. 21', 1931- Qttomeg5 Oct. 3, 1933. F. Lurz 929,322

CHAIN STITCH SEWING MACHINE Filed Aug. 21, 1 931 6 Shets-Sheet 3 Oct. 3, 1933. LUTZ GH'AIN STITCH SEWING MACHINE Filed Au 21, 1931 6 Sheets-Sheet 4 Gttomegs Oct. 3, 1933 F. LUTZ I 1,929,322

CHAIN STITCH SEWING MACHINE Gttornqm Oct. 3, 1933.

01mm STITCH SEWING MACHINE Fil'ed Aug. 21, 193;

6 Sheets-Sheet 6 F. LUTZ 1,929,322 I Patented Got. 3, i933 1,929,322 CHAIN STITCH 'SEWING MACHINE Friedrich Lutz, Stuttgart, Germany, Union Special Maschinenfabrik Stuttgart, Germany Application August 21, 1931,

assignor to G. in. b. 11.,

Serial No. s,5s5,

and in Germany March 24, 1931 10 Claims.

The invention relates to new and useful improvments in single thread chain stitch sewing machines. In a companion application, I have shown and described a single chain stitch sewing machine which is especially adapted for the closing of holes in fabrics, by forming a line of enchained thread loops which is attached to the fabric and which covers and closes the opening. In said co-pending application, the looper is a non-thread carrying looper, and is given a rotation while in the needle thread loop for the purpose of placing the needle thread loop on the needle. The present applicationis an improvement on the machine in this copending application.

An object of the present invention is to provide a more efficient means for rotating the looper and also means associated with the looper for guiding and directing the needle.

A further object of the invention is to provide a more eiiicient means for reciprocating the needle and giving a dwell thereto during the time when the looper is being reversely rotated for the placing of the needle thread loop on the looper about the needle.

A still further object of the invention is to provide an improved 'means for raising the presser foot whereby the tension of the spring normally urging the presser foot on to the material is decreased by the upward movement of the needle bar so that the fabric may be more easily fed by hand in any desired direction.

In the drawings- Figure l is a view in vertical section through va machine embodying the'improvements;

Fig. 2 is a view partly in plan and partly in section showing the drum for imparting movements to the needle and to the looper and also the rack for rotating the looper:

Fig. 3 is a vertical sectional View through the standard of the machine showing the means actuated by the drum which imparts movements to the looper;

Fig. 4 is a view partly in end elevation of the machine with the cover plate for the needle head removed, and partly in section through the work arm showing the mounting for the looper;

Fig. 5 is an end view of the overhanging arm with the cover plate removed and showing the presser foot as lifted from the fabric and the spring for the presser foot released;

Fig. 6 isa view similar to Fig. 5, showing the spring under tension and the presser foot bearing on the work support;

Fig. '7 is a detail showing the cam for lifting view through the presser point is entering the needle thread loop;

Fig. 10 is a plan view of certain of the parts shown in Fig. 9;

Fig. 11 is a diagrammatic view showing the needle reciprocating mechanism;

Fig. 12 is a diagram showing the relative timing of the needle, the oscillations of the looper and the rotations of the looper;

Fig. .13 is a diagrammatic view showing the looper after it has been rotated about the axis of the needle through an arc of 360 degrees, with the point of the needle slightly below the top of the blade of the looper;

Fig. 14 is a similar view, but showing the looper as having rotated in a reverse direction through an arc of 180 degrees, and as having I placed one strand of the needle thread loop on the looper against the face of the needle adjacent its point, and '80 Fig. 15 is a view similar to that shown in Fig. 14, but showing the looper as having been rotated in the reverse direction through an arc of 360 degrees, and as having placed the looper thread loop about the needle so as to insure the needle entering the needle thread loop on its down-stroke.

The invention is directed to an improvement in a single chain stitch machine for forming enchained thread loops for closing openings, such for example, as the darning of holes in bags. The machine includes a needle and a looper which is a non-thread carrying looper and which cooperates with the needle in forming the single chain stitches. The looper is moved into the needle thread loop and comes to a dwell at the forward end of its stroke. The needle is given.

a dwell when the point of the needle has passed well below the upper edge of the blade of the looper. The needle is given a reciprocation by a bodily rotating member, which in turn is rotated and is provided with a crank connected by a link to the needle bar. The arrangement is such that the needle on its down-stroke is given a substantial dwell at the time stated. The looper is oscillated by a link and lever connection to a drum on the main shaft. The looper is rotated by a rack which is moved endwise by a link and lever connection to a drum on the main shaft. Just beneath the looper blade are needle guides for directing the needle so as to insure that the looper will properly pass the needle in entering the needle thread loop. The presser foot is particularly constructed so as to take care of any unevenness in. the fabric sections being stitched. The presser bar carrying the presser foot is urged downwardly by a spring which is put under tension by the needle bar on its downward stroke. On the upward stroke of the needle bar, the tension of the spring is released in part, and the presser foot is lifted at this time by a cam rotating with the needle actuating mechanism.

Referring more in detail to the drawings, the improvements are embodied in a machine which includes a supporting standard 1 carrying an overhanging arm 2 in which the main operating shaft 3 is mounted for rotation. Projecting from the standard 1 is a work supporting arm 4 which is generally of a cylindrical character. At the forward end of the overhanging arm 2 is a needle head in whicha needle bar 5 is mounted for reciprocation. Said needle bar carries a needle 6. The main shaft 3 extends through a stationary bearing sleeve 7 which is provided with a pinion 8. This sleeve is held from rotation by a set screw 9, and this holds the pinion stationary. Secured to the shaft is a casing 10 which rotates with the shaft. Mounted in this casing is a pinion 11 which meshes with the stationary pinion 8. This pinion 11 carries a crank pin 12. A link 13 connects the crank pin to a pin carried by a collar clamped to the needle bar. As the main shaft rotates, the casing 10 will be rotated therewith, and this will cause the pinion 11 to travel bodily in a path about the axis of the shaft, which path isconcentric to the axis of the shaft. As the pinion travels, it rotates, and the pinions are so proportioned that the crank pin 12 carried by the pinion 11 will make one complete rotation about the axis of the pinion 11 for each rotation of the main shaft.

Referring to Fig. 11, the movement imparted to the needle bar is indicated diagrammatically. The needle bar is indicated at 5; the axis of the main shaft at 2; the traveling pinion at 11; the crank pin at 12, and the link connecting the crank pin to the needle bar at 13. When the crank pin is moving'from the position 12 to the position 12*, the needle bar is moving upwardly to the upper end of its stroke. 0n the downward stroke of the needle bar, there is a sub stantial dwell in the movement thereof when the crank pin reaches the position 12. In Fig. 12 of the drawings, the movement of the needle bar is indicated by the curved line :c, w. It will be noted from this diagram that the needle bar moves quickly on its up-stroke to the'point 11:. It then moves downwardly, and from the point 162 to the point :8 it is substantially at a dwell.

Mounted on the work supporting arm 4 is a cloth supporting plate 14 having an opening therethrough for the needle. The material is held on the cloth plate by means of a presser foot 15. The presser foot is carried by a presser bar 16. The presser foot, as shown in Fig. 8, is formed in two sections under surface with slots through the side walls thereof. The lower portion 15 of the presser foot is curved to fit this spherical surface and is provided with bolts 17, 17 which are threaded into the outer foot portion and pass through these slots in the inner portion 15 with the bolts yieldingly hold the two parts in set positions relative to each other. The slots are' of The inner section 15 has a spherical Springs l8, l8 associated sufficient size to permit the under or main portion 15 of the presser/foot to shift on the inner portion to accommodate any unevenness in the fabric sections.

The presser foot is forced downwardly by a spring 19 which surrounds the presser bar and bears at its lower end against a collar 20 attached to the presser bar. This spring bears at its upper end against the forked arm 21 of a collar 22 which is clamped to the needle bar. Said forked arm can slide up and down on the presser bar, and when the needle moves downward, said arms will compress the spring 19, putting it under tension, which tends to force the presser bar downward and the presser foot into engagement with the material. On the up-stroke of the needle bar, these arms 2l-will move away from the collar 20 and release the tension on the spring 19. When the needle bar is at the upper end of its stroke, the tension on the spring 19 is released, so that the presser bar may be readily lifted.

The means for lifting the presser bar is shown in Figures 1 and '7. Mounted on the casing 10 which rotates with the main shaft 3 is a cam 23. Mounted in a sleeve 24 in the needle head is a bar 25 carrying-a roller 26 at the lower end thereof. This bar is clamped to an arm 27 which is also clamped to the presser bar. As this cam 23 rotates. it will engage the roller 26, raise the bar 25, which will in turn raise the presser bar, lifting the presser foot from the material as shown in Fig. 5. The cam is timed so as to lift the presser bar when the needle bar is at the upper end of its stroke and the tension on the spring 19 released.

Cooperating with the needle beneath the work support is a looper 28 which is a non-thread carrying looper. The looper blade has a point which is adapted to enter the needle thread loop. The looper is carried by a shank 29 which is mounted in the looper carrier 30. The looper carrier 30 is attached to a shaft 31 mounted in supporting sleeves 32, 32 carried by a looper support 33. The looper is oscillated on its support, and during its oscillations, the shaft 31 turns in these supporting sleeves 32. The looper is oscillated by means of a rod 34 which is attached to a head 35 engaging a ball 36 formed in the shank 29 supporting the looper. The other end of the rod is connected to a lever 37 which is mounted for free oscillation on a cross shaft 38. At the upper end of the lever 3'? there is a roller running in a cam groove 39 in a drum 40 secured to the main shaft 3. As the rod is moved back and forth, it will oscillate the looper,

moving it into and out of the needle thread loop. This groove 39 which oscillates the looper, is so shaped that the looper is given an extended dwell when at the forward end of its stroke. The dot and dash line y, y in Fig. 12 indicates the movement of the oscillating looper. As the needle starts upward, the looper moves forward into the needle loop very quickly and then comes to a dwell, and is at a dwell from the point y to the point 11 During this dwell in the looper, the needle moves upward to the upper end of its stroke, thence downward, dwelling as described above, and finally the looper is retracted as the needle is approaching the lower end of its stroke.

The support 33 for the looper is mounted for rotation substantially about an axis in line with the needle. The support is provided with. a coneshaped member 41 engaging a bearing sleeve 42 mounted in the work arm. It is also attached to a cone member 43 engaging the bearing sleeve 42 at the lower end thereof. Intermediate the ends, the looper support is provided with a pinion 44 which meshes with a rack'bar 45. The rack bar 45 is provided with cylindrical portions at its ends fitting within a sleeve 46. The bore in the sleeve is eccentric to the axis of the sleeve so that when the sleeve is rotated, the rack bar will be shifted toward and from the pinion 44 with which it meshes. The sleeve may be rotated by aid of the closure screw .47 (see Fig. 2). The rack bar is reciprocated by means of a rod 48 which is pivotally connectedto the end of the rack bar. This rod is also pivoted to the end of a lever 49 which cooperates with a groove 50 in the drum 40. This groove 50 is soshaped and disposed relative to the groove 39 that the looper is rotated first in one direction and then the other through substantially a complete rotation of 360' degrees while the looper is at the forward end of its stroke. In Fig. 12, the movement of rotation which is imparted to the looper is indicated by the broken dash line. The looper is at a rest, so far as rotation is concerned, when it. -is oscillated and moved forward into the needle thread loop. At the point z, the looper begins its rotation, and at this time, the needle is on its up'-stroke, and the looper is at the forward end of its stroke, and has come to the point 11' where it is at a dwell. The looper is rotated, therefore, on the up-stroke of the needle, and will give a twist to the shank of the needle thread loop which is on the looper. This twisting of the looper thread does not, in any way, function in the stitch formation, but is merely a positioning of the looper preparatory to placing the needle thread loop about the needle on its reverse rotation. When i he needle comes to the dwell at the point :2 as indicated in Fig. 12, the needle point is slightly below the upper edge of the blade of the looper as indicated in Fig. 13; The-twist in the thread loops is not indicated in the drawings for the sake of cleamess. The looper, however, has made its complete rotation, and the needle has reached the point where it comes to a dwell, and the looper is about to be turned in a reverse direction for the placing of the needle thread loop on the needle. when the looper I moves from the point z to the point 2 which is given its reverse movement through an arc of approximately 360' degrees, it moves from the position shown in Fig. 13 .to the position shown in Fig. 14, and during this time, the strand 1:. of the needle thread loop is positively carried against tlna face of the needle. The looper blade travels bodily around the needle. In Fig. 13 it is shown as in rear of the needle point. In Fig. 14

it is in front of the needle point. As the looper continues to rotate to the position shown in Fig. 15, this strand #1 of the needle thread loop on the looper will be carried about the needle and 1 placed against the face of the needle between the eye and the point of the needle. The looper then comes to a standstill and remains at a dwell while the needle -continues its stroke to the point a: as indicated in Figure 12. This insures that the needle thread loop will be placed around the needle to positively insure that the needle will enter the needle thread loop. V

Associated with the looper are two needle guards or guides 51, 51 (see Figures 9 and 10).

. These needle guides are secured to the looper beneath the blade thereon, and are so positioned that when the looper moves forward, the guides will first pass the needle, and if it is deflected from its proper position, will insure that it be placed H so that theflooper will pass the needle on the right side thereof and close to the needle as it enters the needle thread loop. A guide plate 52 is attached toa vertical web carried by the work arm for preventing the rod 34 from lateral movement during the rotation of the looper. The rack bar and the pinion operated thereby are lubricated by means of a-port 53 which leads through a sleeve into the inner chamber thereof.

The operation of the machine will be obvious from the detafl description which has been given. The needle passes through the work support and throws out its loop which is engaged by the non-thread carrying looper. The looper when it reaches the forward end of its stroke, remains at a-dwell while it is rotated in first one direction and then the other. The needle, after it has passed through the work support so that its point is a slight distance below the upper edge of the looper blade, remainsat a dwell. The looper also remains at a dwell at this time so far as its oscillations are concerned, and is rotated in a reverse direction for positively placing the needle thread loop carried thereby about the needle. When the needle reacheskthe upper end of its stroke, it releases the tension on the spring, 10c forcing the presser foot downward, and the presser foot is also lifted so as to permit the material to be freely turned and fed in any direction.

It is obvious that minor changes in the details of construction may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to secure by Letters-Pat- 11-.) cut, is-- 1. The combination of a needle, means for reciprocating the same, a 'non-thread carrying looper, means for moving the looper into and'out of the needle thread loop, means carried by and moving with the looper for positioning the needle so as to insure that the'looper will enter the needle thread loop, and means for rotating the looper about an axis substantially parallel with the path of reciprocation of the needle and while in the needle thread loop for positively placing the needle thread loop carried thereon about the needle.

2. The combination of a needle, means for reciprocating the same, a non-thread carrying looper, means for moving the looper into and out of the needle thread loop, needle guides carried by the looper and movable on opposite sides of the path of the needle for positioning the needle so as to insure that the looper will enter the needle thread loop, and means for rotating the 1g looper about an axis substantially parallel with the path of reciprocation of the needle and while in the needle thread loop for positively placing the needle thread loop carried thereon about the needle. 13;

3. The combination of a needle, means for reciprocating the same, a non-thread carrying looper, a support mounted for rotation about an axis substantially parallel with the path of reciprocation of the needle and on which said looper is mounted for oscillation, means for oscillating said looper relative to said rotatable support for moving the same into and out of the needle thread loop, a pinion attached to said support, and a lon-' gitudinally reciprocating rack bar engaging said pinion for rotating the looper support while the looper is in the needle thread loop, for positively placing the needle thread loop carried thereon about the needle.

4. The'combination of a needle, means for reciprocating the same, a non-thread carrying looper, means for oscillating said looper for moving the same into and out of the needle thread loop, a support mounted for rotation about an axis substantially parallel with the path of reciprocation of the needle and on which said looper is mounted for oscillation, a pinion attached to said support, a longitudinally reciprocating rack bar engaging said pinion for rotating the looper support while the looper is in the needle thread loop for positively placing the needle thread loop carried thereon about the needle, a sleeve having a recess in which said rack bar is mounted for reciprocation, said recess being eccentric to the outer face of the sleeve, and means for supporting said sleeve whereby it may be rotated for shifting the position of the rack bar relative to the pinion with which it meshes.

5. The combination of a shaft, a drum carried thereby, a needle bar, a needle carried by the needle bar, means operated by said shaft for reciprocating said needle bar, a non-thread carrying looper cooperating with said needle, a looper carrier on which said looper is mounted, a rotatable support on which said looper carrier is mounted for oscillation, means connected with the looper carrier for oscillating the same relative to said rotatable support, and means connected with said support for rotating the support, said looper oscillating means and said looper rotating means being actuated from said drum.

6. The combination of a main shaft, a drum carried thereby having cam grooves therein, a needle bar, a needle carried thereby, means actuated by said shaft for reciprocating said needle bar, a non-thread carrying looper cooperating with the needle, a looper carrier on which the looper is mounted, a rotatable support on which said looper carrier is mounted for oscillation, a rod connected to the looper carrier for oscillating the same relative to said rotatable support, a lever to which said rod is attached, said lever having a roller running in one of the cam grooves in said drum, a pinion attached to said looper support for rotating the same, a rack bar engaging said pinion, a rod attached to said rack bar, and a lever to which said rod is connected, said lever having a roller running in the other cam means for rotating the looper bodily about the axis of the needle when the looper is in the needle thread loop, said crank pin being so disposed as to give an extended dwell to the needle when the point thereof is slightly below the upper edge of the looper.

8. The combination of a'work support, a presser foot, a presser bar carrying said presser foot, 8. spring forcing said presser bar downwardly, a needle bar, a needle carried thereby, means for reciprocating said needle bar, a non-thread carrying looper cooperating with said needle, means for oscillating said looper, means for rotating said looper about an axis containing the needle when the looper is in the needle thread loop, means carried by the needle bar and engaging the spring operating on the presser bar for placing said spring under tension when the needle is in the material, and for releasing said spring from tension when the needle is at the upper end of its stroke, and means for lifting the presser bar when the needle is at the upper end of its stroke.

9. The combination -of a needle bar, a needle carried thereby, a rotating shaft, a casing carried by said shaft, a pinion mounted in said casing and traveling bodily about the axis of the shaft, a stationary pinion meshing with said traveling pinion, a crank pin carried by said traveling pinion, a link connecting said crank pin to the needle bar, a non-thread carrying looper cooperating with said needle, means for oscillating said looper and giving a dwell thereto at the forward end of its stroke, and means for rotating the looper when in the needle loop, said traveling pinion being so disposed as to give a dwell to the needle bar when the point of the needle is a slight distance below the upper edge of the looper.

10. The combination of a needle bar, a needle carried thereby, a non-thread carrying looper cooperating with said needle, means for reciprocating the needle and giving a dwell thereto with the point slightly below the upper edge of. the looper, means for oscillating the looper and giving a dwell thereto at the forward end. of its stroke, means for rotating the looper while at the forward end of its stroke about an axis containing the needle for placing the needle thread loop on the looper about the needle, a preser foot bearing on the material, and means for automatically lifting the presser foot to release the material at each stitch, said presser foot having a fabric engaging portion provided with a spherical surface at its upper side adapted to engage a spherical surface on the supporting shank of the presser foot, said fabric engaging surface being shiftable on the shank to accommodate varying thicknesses of material.

FRIEDRICH LUTZ. 

